7,826 research outputs found

    Spectroscopic characterization of X-ray emitting young stars associated with the Sh 2-296 nebula

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    We studied a sample of stars associated with the Sh 2-296 nebula, part of the reflection nebulae complex in the region of Canis Major (CMa R1). Our sample corresponds to optical counterparts of X-ray sources detected from observations with the XMM-Newton satellite, which revealed dozens of possible low-mass young stars not yet known in this region. A sample of 58 young star candidates were selected based on optical spectral features, mainly H{\alpha} and lithium lines, observed with multi-objects spectroscopy performed by the Gemini South telescope. Among the candidates, we find 41 confirmed T Tauri and 15 very likely young stars. Based on the H{\alpha} emission, the T Tauri stars were distinguished between classical (17%) and weak-lined (83%), but no significant difference was found in the age and mass distribution of these two classes. The characterization of the sample was complemented by near- and mid-infrared data, providing an estimate of ages and masses from the comparison with pre-main-sequence evolutionary models. While half of the young stars have an age of 1-2 Myrs or less, only a small fraction (~25%) shows evidence of IR excess revealing the presence of circumstellar discs. This low fraction is quite rare compared to most young star-forming regions, suggesting that some external factor has accelerated the disc dissipation

    Realistic shell model and nuclei around 132Sn

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    This contribution reports on a shell-model study of nuclei in the 132Sn region employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential renormalized through the use of the Vlow−k approach. We shall focus on some selected results for nuclei with a few valence particles and/or holes with respect to 132Sn, namely Sn isotopes with N > 82 and 130Te, which have, in part, been discussed in previous papers. Results are compared with experiments, and predictions that may provide guidance to future experiments are also discussed. It is the aim of this contribution to underline the importance of studying 132Sn neighbours to acquire a deep understanding of nuclear structure, that may be very useful also in other physics fields, and to show that the realistic shell model is a very effective tool to conduct these studies

    A quasi-static nonlinear analysis for assessing the fire resistance of 3d frames exploiting time-dependent yield surface

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    In this work an automatic procedure for evaluating the axial force-biaxial bending yield surface of reinforced concrete sections in fire is proposed. It provides an accurate time-dependent expression of the yield condition by a section analysis carried out once and for all, accounting for the strength reduction of the materials, which is a function of the fire duration. The equilibrium state of 3D frames with such yield conditions, once discretized using beam finite elements, is formulated as a nonlinear vectorial equation defining a curve in the hyperspace of the discrete variables and the fire duration. A generalized path-following strategy is proposed for tracing this curve and evaluating, if it exists, the limit fire duration, that is the time of exposure which leads to structural collapse. Compared to the previous proposals on the topic, which are limited to local sectional checks, this work is the first to present a global analysis for assessing the fire resistance of 3D frames, providing a time history of the fire event and taking account of the stress redistribution. Numerical examples are given to illustrate and validate the proposal

    Tolerancia y sociedad multicultural

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    El compendio de las "res novae". A propósito del compendio de la doctrina social de la Iglesia

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    El Compendio de la Doctrina Social de la Iglesia es más que un resumen actualizado del Magisterio acerca de las cuestiones sociales. En las páginas del Compendio puede descubrirse una novedad de fondo, fruto del m€- todo que emplea la Doctrina Social de la Iglesia: la Iglesia ha penetrado con una mirada iluminada por la fe la realidad social actual, y describe en el Compendio el panorama de la dimensidn social del mundo con sus luces y sus somhras. Siguiendo el sendero de la glohalizacidn, se presentan las novedades del mundo del trabajo, la economfa, la ecologi'a, etc

    Contribución de la empresa al desarrollo y Doctrina Social de la Iglesia.

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    La contribución de las empresas al desarrollo, especialmente en los países en vías de desarrollo, es un tema de interés creciente. La conciencia de la necesidad de un desarrollo económico más equilibrado ha dado lugar a algunas concepciones de la actividad empresarial que son analizados desde el punto de vista de la Doctrina Social de la Iglesia. Se subrayan los aspectos comunes entre una concepción inspirada en el llamado «desarrollo sostenible» y la idea que la Iglesia tiene sobre el desarrollo. No obstante, desde la perspectiva moral de la Iglesia Católica, algunas ideas predominantes necesitan una fundamentación más profunda y otras tendrían que ser definitivamente cambiadas si se quiere fomentar un desarrollo humano verdadero

    La empresa como institución mediadora. Un enfoque desde la doctrina social de la Iglesia.

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    A partir de una propuesta de la filosoHa social que considera a la empresa como institución mediadora, se explica la posibilidad de esta concepci6n desde el enfoque de la Doctrina Social de la Iglesia. La actividad empresarial es una de las respuestas a la mision de dominio que corresponde al hombre según el plan de Dios para la creacidn, tal y como aparece en Gen 1, 28. Desde ahí, se pone de manifiesto el papel de la empresa como institucidn mediadora en la medida en que es concebida como «comunidad de personasw, con las consiguientes implicaciones ericas

    Filosofía y teología de los derechos humanos

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    La dignidad del hombre en cuanto imagen de Dios: Tomás de Aquino ante sus fuentes. [Reseña]

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